DFT study of the gas-phase thermal decomposition kinetics of 2-ethoxypyridine into 2-pyridone

The mechanism of the gas-phase elimination kinetics of 2-ethoxypyridine has been studied through the electronic structure calculations using density functional methods: B3LYP/6-31G(d,p), B3LYP/6-31++G(d,p), B3PW91/6-31G(d,p), B3PW91/6-31++G(d,p), MPW1PW91/6-31G(d,p), MPW1PW91/6-31++G(d,p), PBEPBE/6-31G(d,p), PBEPBE/6-31++G(d,p), PBE1PBE1/6-31G(d,p), and PBE1PBE1/6-31++G(d,p). The elimination reaction of 2-ethoxypyridine occurs through a six-centered transition state geometry involving the pyridine nitrogen, the substituted carbon of the aromatic ring, the ethoxy oxygen, two carbons of the ethoxy group, and a hydrogen atom, which migrates from the ethoxy group to the nitrogen to give 2-pyridone and ethylene. The reaction mechanism appears to occur with the participation of p-electrons, similar to alkyl vinyl ether elimination reaction, with simultaneous ethylene formation and hydrogen migration to the pyridine nitrogen producing 2-pyridone. (C) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2011